1. Field of the Invention
The present invention relates to a suspension subframe structure of a vehicle, and more particularly to a suspension subframe structure of a vehicle for supporting a plurality of suspension arms of a multi-link suspension system.
2. Description of the Related Art
Heretofore, a multi-link suspension system called “E-type multi-link suspension system” has been known. JP 2005-193893A (hereinafter referred to as “Patent Document 1”) discloses a structure of a rear suspension subframe for supporting a plurality of suspension arms of an E-type multi-link rear suspension systems.
A conventional subframe, such as the subframe disclosed in the Patent Document 1, comprises a plurality of subframe members each having a rectangular-shaped hollow closed cross-section or an angular C-shaped cross-section, wherein the plurality of subframe members are assembled together in a double cross shape. In the conventional subframe, in order to handle or receive a large input load (such as tensile and compressive loads) from in the suspension arms, particularly, during turning of a vehicle, it is necessary to increase its rigidity by enlarging a cross-sectional area of the subframe member itself or providing a reinforcing member, which leads to a problem about an increase in weight.
Moreover, depending on mounting positions of the suspension arms to the subframe member extending in a frontward-rearward (i.e., longitudinal) direction of the vehicle and the subframe member extending in a widthwise (i.e., lateral) direction of the vehicle, torsional or bending deformation occurs between the subframe members. This is disadvantageous in terms of rigidity and reliability, to cause a further increase in weight.